Manufacture of carbon filaments



(No Model.)

B. P. THOMPSON. MANUFACTURE OF CARBON FILAMENTS.

Patented Apr. 16, 1889.

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UNITED STATES PATENT rricn.

EDWARD P. THOMPSON, OF ELIZABETH, NEIV JERSEY.

MANUFACTURE OF CARBON FILAMENTS.

SPECIFICATION forming part of Letters Patent N 0. 401,606, dated April 16, 1889. Application filed February 4, 1887. Serial No. 226,525. (No model.)

To aZZ whom it 17mg concern: I

Be it known that I, EDWARD P. THOMPSON, a citizen of the United States, residing in Elizabeth, in the count-y of Union and State of New Jersey, have invented certain new and useful Improvements in the Process of Manufacturin g Filaments for Incandescent Electric Lamps, of which the following is a specification.

The invention relates to a process of preparing carbonized filaments and treating them while being built up and formed into the required shape.

The obj eot of the invention is to produce a filament which shall be durable, have as great a density as practicable, and possess the qualities requisite for satisfactory service.

In general terms the invention consists in first washing the carbonized filament with an inert gas while it is incandescent; second, in throwing off the loose particles while it is being so washed by means of a static current or charge; third, in placing the filament under torsional strain, and, if it is desired, at the same time under tension, causing it to break, thus giving a permanent set to its molecules, and afterward building up and forming the filament into the required shape.

The invention will be described in connection with the accompanying drawings, in which- Figure 1 shows, in elevation, an apparatus for carrying out the first steps of the invention, together with a convenient system of circuits; and Fig. 2 illustrates the apparatus employed for forming and building up the filament. Fig. 3 shows a modified device for applying torsion to the filament.

Referring to Fig. 1, A represents a suitable bell-jar or containing-chamber for receiving a filament, B, which is to be treated. This filament extends through a glass tube, 19. The

' filament is held at its respective ends by two suitable clamps, 0' c and the tube rests in any convenient manner upon the lower stationary clamp, c, terminating above or extending within the gas-supply tube cl, extending from any suitable reservoir, D, of hydrogen or inert gas. The clamp c is connected by a conductor, 1, including a suitable resistance, r, with one pole of a generator or other suitable source of electricity, E. The other pole is connected by a conductor, 2, with the clamp 0 A switch, 3, serves to open and close the circuit of the generator through the filament when desired. By placing the filament in circuit and admitting hydrogen through the tube (Z. the filament B will be washed by the gas, which is caused to pass through the tube in contact with the filament. The filament being heated, the rapidity with which the gas passes through the tube is increased, and thus the filament becomes thoroughly washed. This treatment removes from the filament such loose particles as would otherwise be thrown off or removed from the filament after being placed in the lamp by reason of the long-continued action of the attenuated gas within the globe of the lamp, and thusv the blackening of the globe is, to a corresponding extent, prevented. Another advantage resulting from this treatment is that the deposit of carbon, which is subsequently applied, is now made directly upon the solid structural carbon, whereas without such treatment there will necessarily remain upon the filament more or less of the carbon solid basis and is more easily thrown .oftl.

By the present invention however, the deposited carbon becomes firmly attached to the structural carbon or the real base of the filament.

For the purpose of assisting in the removal of the imperfectly-attached carbon, it is usually preferred to send a static charge of electricity to the filament during the process just described, thus combining with the current by which it is heated to throw off whatever carbon may not otherwise be removed by simply washing. This is conveniently accom plished by connecting the opposite poles of any suitable source of static electricity-such, for instance, as aLeyden jar, Fthrough the filament. A convenient method of doing this consists in connecting one pole, f, of the jar,

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such, for instance, as a Holtz machine or an scribed in connection with Fig. 2. This coninductorium. After the filament has been sists in first bending the filament into the rethus treated to the required extent, it is dequired shape in any desired or convenient 7o sired to place it under torsion and to cause it manner and in placing it in suitable supto break while it is still heated by the curports or clamps, n and M. It is then inserted rent from the generator E. This current is in a jar, N, where it is treated by hydrocarpreferablyincreased at the proper moment by bon gas delivered through a pipe, 0, an excutting out any required amount of the rehaust-pipe, being provided for not allowsistance r. The cutting out of this resisting the escape of gas from the chamber. The ance may serve as a test for determining the filament is connected in circuit with a generstrength of the filament to resist fracture unator, E, the amount of current therefrom beder the influence of heat, the amount of curing regulated by a resistance, W, or in any rent which it is desired that the filament shall other convenient manner, and the connecstand without injury having been previously tions of the circuit being controlled by a determined.

switch, 3. The filament is thus built up by The torsion to which the filament is suba deposit of hydrocarbon while it is held in jected is also regulated, and it is previously the proper required shape. The gas applied determined how much torsion it shall be cato the filament in this manner is preferably pable of withstanding. The torsion is conunder greater or less pressure, the amount of veniently applied by means of a revolving which may be readily determined by means support, h, carrying the clamp c and proof a suitable gage, P, applied to the chamber vided with an armature, h. An electr -mag- M in any convenient manner. It is not alnet, H, placed outside the chamber A, is apways necessary to apply the carbon deposit 0 plied to this armature, and by turning it in in the manner just described; but the hydro- 5 its support it will cause the armature h, and carbon gas may be applied to the filament thus the support h, to turn, carrying with it while itis in the chamberA. (Shown in Fig. 1.)

the clamp 0 and thus applying torsion to the Thus it may, for instance, be supplied through filament B.

the tube d, a hydrogen-reservoir being dis- 5 The electro-magnet H may be included in connected. 0 a branch circuit of the generator E, or in any It is not desired to confine the individual suitable manner placed in an electric circuit. methods of treating the filament to this entire The pointer or indicator j serves, when the process; but certain of the steps may be perinclosing walls are of transparent material, to formed without the sequence of the others, if indicate upon the plate j, carrying the supso desired. In some instances it is desired to q 5 port it, the amount of torsion thus applied to reduce the size of the filament by removing I the filament, and whether or not it withstands more or less of the outer surface, and the torthe predetermined requisite amount of torsion sional treatment may be employed without 1 without breaking. A spring, 9' presses breaking the filament during the process of against the support h, and, if it is desired to washing or removing the partially-detached 4,0 place the filament under tension while the particles. The torsion which is put into the torsion is applied, the magnet H is vitalized filament will cause the outer fibers to break, sufiiciently to overcome more or less the tension of the spring, thus raising the support h.

and these may be removed in the manner already described, thus reducing the cross-secno The torsion maybe applied to the filament,

tion of the filament. 5 if desired, before it is placed in the treating- The chamber A is preferably composed of jar A, and this may be conveniently accomsome suitable refractory substancesuch, for plished by constructing the clamp c and its instance, as fire-clay-for the purpose of consupport as shown in Fig. 3, in which the supfining the heat, and this is surrounded by a port h carries a handle, 77/ by means of which glass tube A ,which assists in preventing the 50 it may be conveniently turned above the dial access of air into the chamber by having the A series of holes, is, in the dial-plate reend upon which it rests ground to fit tightly ceives the pin k, carried by the spring-handle to the support or base. Between these two if, for holding the support in any required walls, therefore, there will beaspace occupied 12o position. Thus the filament may be placed by a more or less attenuated gas. 55 under any predetermined tension and held The treatment of the filament by twisting there during the process of treatment. After and heating by the current may be alternated, the filament has been thus treated, it is deif desired, the required amount of torsion thus sired to break it while it is still under torsion, being gradually applied. 12 5 and for this purpose the increased current The filament may be broken by twisting it 60 already referred to is sent through it, its alone without increasing the strength of curstrength being increased to such a point as rent, and a sufficient permanent set may be will cause it to break. The breaking of the obtained in some instances in this manner. filament while thus sub ected to an intense I claim as my invention 0 heat will cause a torsional permanent set of 1. The hereinbefore-described process of 65 the molecules. After the filament has thus treating filaments, which consists in washing :2

been prepared, it is removed from the jar A the same by a current of inert gas, heating and treated in a manner which will be dethe filament while being so washed, and in sending a static charge to said filament While being so washed.

2. The hereinbefore-described process of treating filaments, which consists in removing the loose particles of carbon from the filament by a static charge of electricity and in building up the filament by a deposit of carbon upon the filament, substantially as described.

3. The hereinbefore-described process of treating filaments, which consists in washing the filament by an inert gas, heating the filament to incandescence While being so washed, throwing off the loose particles by one or more static charges, and in subsequently building up the filament by a deposit of carbon.

4. The hereinbeforedescribed process of treating filaments, which consists in washing them with gas while incandescent, subsequently placing them under torsion, and breaking them while under torsion.

5. The hereinbefore-described process of treating filaments, which consists in washing them with gas while incandescent, subsequently placing them under torsion, and in heating them by an increased current until they break.

6. In an apparatus for treating filaments for incandescent electric lamps, the combination, with an inclosing-case, of clamps for supporting the filament, a revolving support for one of the clamps, an armature carried thereby, and an electro-magnet outside of said case for revolving the armature.

7. In an apparatus for treating filaments for incandescent electric lamps, the combination, with an inclosing-case, of clamps for supporting the filament, a revolving support for one of the clamps, an armature carried thereby, an electro-magnet outside of said case for revolving the armature, and a spring acting in opposition to the longitudinal pull of said electro-magnet.

In testimony whereof I have hereunto subscribed my name this 2lst day of January, A. D. 1887.

EDWARD P. THOMPSON.

Witnesses:

DANL. W. EDGECOMB, CHARLES A. TERRY. 

